Yo thanks for the in depth comments! And for hosting this lovely event!
I hear your pain and frustration regarding Development Default and Glorbbz Revenge levels in particular and your confusion more generally regarding the gameplay experience. We spent too much time on the level editor (available on steam version only) and didn't make the levels good enough or flow well enough. I think our next turn of the crank will focus on what you described with the teaching of each block individually maybe with "biome" type level design that really focuses on each block one at a time. A little "map" or something of levels youve completed and bundling levels into categories might help a bit as well.
For the jumping sound that was me having fun with my first attempts at foley but I agree it's a bit odd to have a marble / ball making a human jumping sound 😅 I'll likely swap that one out or at least try some other ones that are more fitting. Cheers!